Organic electroluminescent materials and devices

ABSTRACT

A compound according to a formula I, devices incorporating the same, and formulations including the same are described. The compound according to the formula I can have the structure 
                         
wherein R 1 , R 2 , R 3 , R 4 , R 5  and R 6  each represent mono, di, tri, tetra substitutions, or no substitution, R 9  represents mono, di, tri substitutions, or no substitution, R 1 , R 2 , R 3 , R 4 , R 5 , R 6  and R 9  are each independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. A 1 , A 2 , A 3 , A 4 , A 5 , and A 6  are each independently selected from N or C and n is an integer from 1 to 20.

PARTIES TO A JOINT RESEARCH AGREEMENT

The claimed invention was made by, on behalf of, and/or in connectionwith one or more of the following parties to a joint universitycorporation research agreement: Regents of the University of Michigan,Princeton University, The University of Southern California, and theUniversal Display Corporation. The agreement was in effect on and beforethe date the claimed invention was made, and the claimed invention wasmade as a result of activities undertaken within the scope of theagreement.

FIELD OF THE INVENTION

The present invention relates to organic light emitting devices (OLEDs),and more specifically to organic materials used in such devices. Morespecifically, the present invention relates to host compounds forphosphorescent OLEDs.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting devices (OLEDs), organic phototransistors, organic photovoltaiccells, and organic photodetectors. For OLEDs, the organic materials mayhave performance advantages over conventional materials. For example,the wavelength at which an organic emissive layer emits light maygenerally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Color may be measured using CIE coordinates, which are wellknown to the art.

One example of a green emissive molecule is tris(2-phenylpyridine)iridium, denoted Ir(ppy)₃, which has the following structure:

In this, and later figures herein, we depict the dative bond fromnitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY OF THE INVENTION

According to an embodiment of the present disclosure, a compound or acomposition comprising such a compound is provided. The compoundcomprises triphenylene, carbazole and at least one spacer linkagebetween triphenylene and carbazole. The compound provided in the presentdisclosure has a general structure of the formula I:

wherein R¹, R², R³, R⁴, R⁵ and R⁶ each represent mono, di, tri, tetrasubstitutions, or no substitution, R⁹ represents mono, di, trisubstitutions, or no substitution, R¹, R², R³, R⁴, R⁵, R⁶ and R⁹ areeach independently selected from the group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof. A¹, A², A³, A⁴, A⁵, and A⁶ are each independently selected fromN or C and n is an integer from 1 to 20.

According to another embodiment of the present disclosure, a firstdevice comprising an organic light-emitting device is provided. Thefirst device comprises an anode, a cathode, and an organic layer. Theorganic layer is disposed between the anode and the cathode, andcomprises a compound having formula I or a composition comprising acompound having formula I. The compound can be used alone or incombination of other materials in the organic layer for differentfunctions. For example, in some embodiments, the organic layer is anemissive layer and the compound of the formula I is a host material. Thecompound of the formula I can be also used as a blocking material or anelectron transporting material. The first device can be a consumerproduct, an organic light-emitting device, and/or a lighting panel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows Formula I as disclosed herein.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed, light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporatedby reference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, a cathode 160, and a barrier layer 170.Cathode 160 can be a compound cathode having a first conductive layer162 and a second conductive layer 164. Device 100 may be fabricated bydepositing the layers described, in order. The properties and functionsof these various layers, as well as example materials, are described inmore detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which areincorporated by reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F₄-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. Pat. No. 7,431,968, which is incorporated by reference in itsentirety. Other suitable deposition methods include spin coating andother solution based processes. Solution based processes are preferablycarried out in nitrogen or an inert atmosphere. For the other layers,preferred methods include thermal evaporation. Preferred patterningmethods include deposition through a mask, cold welding such asdescribed in U.S. Pat. Nos. 6,294,398 and 6,468,819, which areincorporated by reference in their entireties, and patterning associatedwith some of the deposition methods such as ink-jet and OVJD. Othermethods may also be used. The materials to be deposited may be modifiedto make them compatible with a particular deposition method. Forexample, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processibility than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the presentinvention may further optionally comprise a barrier layer. One purposeof the barrier layer is to protect the electrodes and organic layersfrom damaging exposure to harmful species in the environment includingmoisture, vapor and/or gases, etc. The barrier layer may be depositedover, under or next to a substrate, an electrode, or over any otherparts of a device including an edge. The barrier layer may comprise asingle layer, or multiple layers. The barrier layer may be formed byvarious known chemical vapor deposition techniques and may includecompositions having a single phase as well as compositions havingmultiple phases. Any suitable material or combination of materials maybe used for the barrier layer. The barrier layer may incorporate aninorganic or an organic compound or both. The preferred barrier layercomprises a mixture of a polymeric material and a non-polymeric materialas described in U.S. Pat. No. 7,968,146, PCT Pat. Application Nos.PCT/US2007/023098 and PCT/US2009/042829, which are herein incorporatedby reference in their entireties. To be considered a “mixture”, theaforesaid polymeric and non-polymeric materials comprising the barrierlayer should be deposited under the same reaction conditions and/or atthe same time. The weight ratio of polymeric to non-polymeric materialmay be in the range of 95:5 to 5:95. The polymeric material and thenon-polymeric material may be created from the same precursor material.In one example, the mixture of a polymeric material and a non-polymericmaterial consists essentially of polymeric silicon and inorganicsilicon.

Devices fabricated in accordance with embodiments of the invention maybe incorporated into a wide variety of consumer products, including flatpanel displays, computer monitors, medical monitors, televisions,billboards, lights for interior or exterior illumination and/orsignaling, heads up displays, fully transparent displays, flexibledisplays, laser printers, telephones, cell phones, personal digitalassistants (PDAs), laptop computers, digital cameras, camcorders,viewfinders, micro-displays, vehicles, a large area wall, theater orstadium screen, or a sign. Various control mechanisms may be used tocontrol devices fabricated in accordance with the present invention,including passive matrix and active matrix. Many of the devices areintended for use in a temperature range comfortable to humans, such as18 degrees C. to 30 degrees C., and more preferably at room temperature(20-25 degrees C.).

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

The terms for chemical substitution groups such as halo, halogen, alkyl,cycloalkyl, alkenyl, alkynyl, arylkyl, heterocyclic group, aryl,aromatic group, and heteroaryl are known to the art, and are defined inU.S. Pat. No. 7,279,704 at cols. 31-32, which are incorporated herein byreference.

In the chemical formulas in the present disclosure, either a solid lineor a dotted line represents a chemical bond or multiple chemical bonds.Unless expressly stated otherwise, the solid lines and the dotted linesdo not represent spatial arrangements of chemical bonds instereochemistry. A solid line or a dotted line across a chemicalstructure such as a ring or a fused ring represents either one chemicalbond or multiple bonds connected with one or multiple possible positionsof the chemical structure.

Triphenylene containing compounds provide excellent stability inphosphorescent OLEDs (PHOLEDs). Carbazole containing compounds have beenused as host materials in the emissive layers in PHOLEDs.4,4′-di(9H-carbazol-9-yl)-1,1′-biphenyl (CBP) is a commonly usedcarbazole containing host for green PHOLEDs. However, the lifetime ofthe devices that use CBP as a host does not meet commercialrequirements. It has been found that carbazole can undergo oxidativecoupling to form bicarbazole when it is oxidized. This instability ofcarbazole to positive charges may translate into the poor devicelifetime of PHOLEDs that contain carbazole group in the host material.

According to an embodiment of the present disclosure, a compound or acomposition comprising a compound that comprises triphenylene, carbazoleand at least one spacer linkage between triphenylene and carbazole isdisclosed as a host material for PHOLEDs that enhances the lifetime ofPHOLEDs. As shown in FIG. 3, the compound has a general structure of theformula I:

wherein R¹, R², R³, R⁴, R⁵ and R⁶ each represent mono, di, tri, tetrasubstitutions, or no substitution. R⁹ represents mono, di, trisubstitutions, or no substitution. R¹, R², R³, R⁴, R⁵, R⁶ and R⁹ areeach independently selected from the group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof. A¹, A², A³, A⁴, A⁵, and A⁶ are each independently selected fromN or C and n is an integer from 1 to 20.

Combining the triphenylene group and carbazole group in a host compoundwould not be expected to solve the oxidation problem becausetriphenylene is even harder to oxidize. However, the inventors haveunexpectedly discovered that the combination of triphenylene andcarbazole in certain manners in a host compound can improve PHOLEDs'device lifetime. Without being bound by any theory, the inventorsbelieve that this unexpected improvement may be related to solid statepacking and charge transport properties.

In some embodiments, the compound provided in the present disclosure hasthe formula II, III, IV or V:

wherein the substitution groups are the same as described in the formulaI.

In some embodiments, the compound provided in the present disclosure hasthe formula VI:

wherein R⁷ and R⁸ are each independently selected from the groupconsisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof. Other groups are the sameas described in the formula I.

In some embodiments, the functional groups of R¹, R², R³, R⁴, R⁵, R⁶ andR⁹ in the formulas I, II, III, IV, V and VI are each independentlyselected from the group consisting of hydrogen, deuterium, silyl, aryl,and heteroaryl.

In some embodiments, the compound provided in the present disclosure hasthe formula VII:

wherein the substitution groups are the same as described in the formulaI, and n is an integer from 1 to 5.

In some embodiments, in the compound having the formula VII, n is aninteger from 1 to 3 and R¹, R², R³, R⁴, R⁵, R⁶ and R⁹ are eachindependently selected from the group consisting of hydrogen and phenyl.For example, n is 1 and R¹, R², R³, R⁴, R⁵, R⁶ and R⁹ are hydrogen.

In some embodiments, in a compound provided in this disclosure, at leastone of A¹, A², A³, A⁴, A⁵, and A⁶ is N (nitrogen). The compound has thegeneral formula VIII or IX:

wherein the substitution groups are the same as described in the formulaI and n is an integer from 1 to 5.

In some embodiments, in the compound having the formula VIII or IX, n isan integer from 1 to 3 and R¹, R², R³, R⁴, R⁵, R⁶ and R⁹ are eachindependently selected from the group consisting of hydrogen and phenyl.For example, n is equal to two in some embodiments.

In some embodiments, examples of compounds having the formula I includebut are not limited to the following compounds (compounds 1-53):

A composition comprising a compound represented by the formula Idescribed above is also provided in the present disclosure. Suchcomposition can be formulated with other materials suitable for organiclight emitting applications. Examples of other suitable materialsinclude but are not limited to a host compound, a phosphorescent dopant,a blocking material, an electron transporting material, an additive, andany combination thereof. Examples of compounds having the formula I canhave general structures as described in the formulas I-IX. Examples of asuitable exemplary compound include but are not limited to the followingcompound (compounds 1-53) described above.

According to an embodiment of the present disclosure, a first devicecomprising the organic light-emitting device is provided. The OLEDcomprises an anode, a cathode, and an organic layer disposed between theanode and the cathode. The organic layer comprises a compound having theformula I or a composition comprising a compound having the formula I.

The compound can be used alone or in combination with other materials inthe organic layer for different functions. For example, the compoundhaving the formula I can be also used as a blocking material or anelectron transporting material. The first device can be a consumerproduct, an organic light-emitting device, and/or a lighting panel.

According to the present disclosure, the compounds provided in thepresent disclosure give good results in green PHOLEDs as a host materialin the emissive layer. In addition, the compounds are soluble in organicsolvents such as toluene. Solution process can be used to be fabricatedhigh performance PHOLED.

Combination with Other Materials

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a widevariety of other materials present in the device. For example, emissivedopants disclosed herein may be used in conjunction with a wide varietyof hosts, transport layers, blocking layers, injection layers,electrodes and other layers that may be present. The materials describedor referred to below are non-limiting examples of materials that may beuseful in combination with the compounds disclosed herein, and one ofskill in the art can readily consult the literature to identify othermaterials that may be useful in combination.

HIL/HTL:

A hole injecting/transporting material to be used in the presentinvention is not particularly limited, and any compound may be used aslong as the compound is typically used as a hole injecting/transportingmaterial. Examples of the material include, but not limit to: aphthalocyanine or porphryin derivative; an aromatic amine derivative; anindolocarbazole derivative; a polymer containing fluorohydrocarbon; apolymer with conductivity dopants; a conducting polymer, such asPEDOT/PSS; a self-assembly monomer derived from compounds such asphosphonic acid and sliane derivatives; a metal oxide derivative, suchas MoO_(x); a p-type semiconducting organic compound, such as1,4,5,8,9,12-Hexaazatriphenylenehexacarbonitrile; a metal complex, and across-linkable compounds.

Examples of aromatic amine derivatives used in HIL or HTL include, butnot limit to the following general structures:

Each of Ar¹ to Ar⁹ is selected from the group consisting aromatichydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl,triphenylene, naphthalene, anthracene, phenalene, phenanthrene,fluorene, pyrene, chrysene, perylene, azulene; group consisting aromaticheterocyclic compounds such as dibenzothiophene, dibenzofuran,dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene,benzoselenophene, carbazole, indolocarbazole, pyridylindole,pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole,oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine,pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine,indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole,benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline,quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine,phenazine, phenothiazine, phenoxazine, benzofuropyridine,furodipyridine, benzothienopyridine, thienodipyridine,benzoselenophenopyridine, and selenophenodipyridine; and groupconsisting 2 to 10 cyclic structural units which are groups of the sametype or different types selected from the aromatic hydrocarbon cyclicgroup and the aromatic heterocyclic group and are bonded to each otherdirectly or via at least one of oxygen atom, nitrogen atom, sulfur atom,silicon atom, phosphorus atom, boron atom, chain structural unit and thealiphatic cyclic group. Wherein each Ar is further substituted by asubstituent selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof.

In one aspect, Ar¹ to Ar⁹ is independently selected from the groupconsisting of:

where k is an integer from 1 to 20; X¹⁰¹ to X¹⁰⁸ is C (including CH) orN; Z¹⁰¹ is NAr¹, O, or S; Ar¹ has the same group defined above.

Examples of metal complexes used in HIL or HTL include, but not limit tothe following general formula:

where Met is a metal; (Y¹⁰¹-Y¹⁰²) is a bidentate ligand, Y¹⁰¹ and Y¹⁰²are independently selected from C, N, O, P, and S, L¹⁰¹ is anotherligand, k′ is an integer value from 1 to the maximum number of ligandsthat may be attached to the metal, and k′+k″ is the maximum number ofligands that may be attached to the metal.

In one aspect, (Y¹⁰¹-Y¹⁰²) is a 2-phenylpyridine derivative.

In another aspect, (Y¹⁰¹-Y¹⁰²) is a carbene ligand.

In another aspect, Met is selected from Ir, Pt, Os, and Zn.

In a further aspect, the metal complex has a smallest oxidationpotential in solution vs. Fc⁺/Fc couple less than about 0.6 V.

Host:

The light emitting layer of the organic EL device of the presentinvention preferably contains at least a metal complex as light emittingmaterial, and may contain a host material using the metal complex as adopant material. Examples of the host material are not particularlylimited, and any metal complexes or organic compounds may be used aslong as the triplet energy of the host is larger than that of thedopant. While the Table 1 below categorizes host materials as preferredfor devices that emit various colors, any host material may be used withany dopant so long as the triplet criteria is satisfied.

Examples of metal complexes used as host are preferred to have thefollowing general formula:

Met is a metal; (Y¹⁰³-Y¹⁰⁴) is a bidentate ligand, Y¹⁰³ and Y¹⁰⁴ areindependently selected from C, N, O, P, and S; L¹⁰¹ is an anotherligand; k′ is an integer value from 1 to the maximum number of ligandsthat may be attached to the metal; and k′+k″ is the maximum number ofligands that may be attached to the metal.

In one aspect, the metal complexes are:

(O—N) is a bidentate ligand, having metal coordinated to atoms O and N.

In another aspect, Met is selected from Ir and Pt.

In a further aspect, (Y¹⁰³-Y¹⁰⁴) is a carbene ligand.

Examples of organic compounds used as host are selected from the groupconsisting aromatic hydrocarbon cyclic compounds such as benzene,biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene,phenanthrene, fluorene, pyrene, chrysene, perylene, azulene; groupconsisting aromatic heterocyclic compounds such as dibenzothiophene,dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran,benzothiophene, benzoselenophene, carbazole, indolocarbazole,pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole,oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole,pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine,oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine,benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline,cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine,pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine,benzofuropyridine, furodipyridine, benzothienopyridine,thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine;and group consisting 2 to 10 cyclic structural units which are groups ofthe same type or different types selected from the aromatic hydrocarboncyclic group and the aromatic heterocyclic group and are bonded to eachother directly or via at least one of oxygen atom, nitrogen atome,sulfur atom, silicon atom, phosphorus atom, boron atom, chain structuralunit and the aliphatic cyclic group. Wherein each group is furthersubstituted by a substituent selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof.

In one aspect, host compound contains at least one of the followinggroups in the molecule:

where R¹⁰¹ to R¹⁰⁷ is independently selected from the group consistingof hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl,arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl,heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylicacids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl,phosphino, and combinations thereof, when it is aryl or heteroaryl, ithas the similar definition as Ar's mentioned above.

k is an integer from 1 to 20; k′″ is an integer from 0 to 20.

X¹⁰¹ to X¹⁰⁸ is selected from C (including CH) or N.

Z¹⁰¹ and Z¹⁰² is selected from NR¹⁰¹, O, or S.

HBL:

A hole blocking layer (HBL) may be used to reduce the number of holesand/or excitons that leave the emissive layer. The presence of such ablocking layer in a device may result in substantially higherefficiencies as compared to a similar device lacking a blocking layer.Also, a blocking layer may be used to confine emission to a desiredregion of an OLED.

In one aspect, compound used in HBL contains the same molecule or thesame functional groups used as host described above.

In another aspect, compound used in HBL contains at least one of thefollowing groups in the molecule:

where k is an integer from 1 to 20; L¹⁰¹ is an another ligand, k′ is aninteger from 1 to 3.ETL:

Electron transport layer (ETL) may include a material capable oftransporting electrons. Electron transport layer may be intrinsic(undoped), or doped. Doping may be used to enhance conductivity.Examples of the ETL material are not particularly limited, and any metalcomplexes or organic compounds may be used as long as they are typicallyused to transport electrons.

In one aspect, compound used in ETL contains at least one of thefollowing groups in the molecule:

R¹⁰¹ is selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof, when it is aryl or heteroaryl, it has the similar definition asAr's mentioned above.

Ar¹ to Ar³ has the similar definition as Ar's mentioned above.

k is an integer from 1 to 20.

X¹⁰¹ to X¹⁰⁸ is selected from C (including CH) or N.

In another aspect, the metal complexes used in ETL contains, but notlimit to the following general formula:

(O—N) or (N—N) is a bidentate ligand, having metal coordinated to atomsO, N or N, N; L¹⁰¹ is another ligand; k′ is an integer value from 1 tothe maximum number of ligands that may be attached to the metal.

In any above-mentioned compounds used in each layer of the OLED device,the hydrogen atoms can be partially or fully deuterated. Thus, anyspecifically listed substituent, such as, without limitation, methyl,phenyl, pyridyl, etc. encompasses undeuterated, partially deuterated,and fully deuterated versions thereof. Similarly, classes ofsubstituents such as, without limitation, alkyl, aryl, cycloalkyl,heteroaryl, etc. also encompass undeuterated, partially deuterated, andfully deuterated versions thereof.

In addition to and/or in combination with the materials disclosedherein, many hole injection materials, hole transporting materials, hostmaterials, dopant materials, exiton/hole blocking layer materials,electron transporting and electron injecting materials may be used in anOLED. Non-limiting examples of the materials that may be used in an OLEDin combination with materials disclosed herein are listed in Table 1below. Table 1 lists non-limiting classes of materials, non-limitingexamples of compounds for each class, and references that disclose thematerials.

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In some embodiments, the organic layer in the first device is anemissive layer and the compound of formula I is a host material. Theorganic layer may further comprise an emissive dopant. The emissivedopant is a transition metal complex having at least one ligand.Examples of the least one ligand include but are not limited to:

Wherein R_(a), R_(b), and R_(c) may represent mono, di, tri or tetrasubstitutions, R_(a), R_(b), and R_(c) are independently selected fromthe group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof, and two adjacentsubstituents of R_(a), R_(b), and R_(c) are optionally joined to form afused ring.

Examples of the transition metal in the emissive dopant include but arenot limited to Ir, Pt, Os, Ru, Au, Cu, and Re and combinations thereof.

EXPERIMENTAL Synthesis of Compound 1

A solution of9-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-9H-carbazole(5.0 g, 13.5 mmol), 2-(3-bromophenyl)triphenylene (4.2 g, 10.8 mmol),Pd₂(dba)₃ (0.20 g, 0.22 mmol), SPhos (0.36 g, 0.87 mmol) and K₃PO₄ (9.2g, 43.3 mmol) in toluene (100 ml) and water (10 ml) was refluxed undernitrogen for 12 h. After cooling to room temperature, it was dilutedwith water and extracted with DCM. The combined organic extracts werewashed with brine and dried over MgSO₄. Upon evaporation off thesolvent, the residue was purified by column chromatography on silica gelwith hexane/DCM (9/1 to 7/1, v/v) as eluent. The crude product wasredissolved in boiling toluene and filtered through a short plug ofsilica gel topped with MgSO₄ to yield Compound 1 (2.5 g, 42%) as a whitesolid.

Synthesis of Compound 2

A solution of4,4,5,5-tetramethyl-2-(3-(triphenylen-2-yl)phenyl)-1,3,2-dioxaborolane(3.6 g, 8.4 mmol), 9-(4-bromophenyl)-9H-carbazole (3.0 g, 9.2 mmol),Pd(PPh₃)₄ (0.19 g, 0.17 mmol) and K₂CO₃ (3.5 g, 25.1 mmol) in toluene(50 ml) and water (25 ml) was refluxed at 110° C. overnight. Aftercooling to room temperature, the organic phase was isolated and theaqueous phase was extracted with dichloromethane. The combined organicsolutions were washed with water and dried over MgSO₄. Upon evaporationoff the solvent, the residue was purified by column chromatography onsilica gel with hexane/DCM (85/15 to 75/25, v/v) as eluent and the crudeproduct was triturated with boiling ethyl acetate to yield Compound 2(3.0 g, 66%) as a white solid.

Synthesis of Compound 5

A solution of4,4,5,5-tetramethyl-2-(3-(triphenylen-2-yl)phenyl)-1,3,2-dioxaborolane(3.0 g, 7.0 mmol), 9-(3′-bromo-[1,1′-biphenyl]-3-yl)-9H-carbazole (2.8g, 7.0 mmol), Pd(PPh₃)₄ (0.24 g, 0.21 mmol) and K₂CO₃ (2.9 g, 20.9 mmol)in toluene (45 ml) and water (15 ml) was refluxed under nitrogenovernight. After cooling to room temperature, the organic phase wasisolated, and the aqueous phase was extracted with DCM. The combinedorganic extracts were washed with water and dried over MgSO₄. Uponevaporation off the solvent, the residue was purified by columnchromatography on silica gel with hexane/DCM (9/1 to 4/1, v/v) as eluentand precipitation in ethanol to yield Compound 5 (2.1 g, 48%) as a whitesolid.

Synthesis of Compound 53

A solution of4,4,5,5-tetramethyl-2-(3-(triphenylen-2-yl)phenyl)-1,3,2-dioxaborolane(3.5 g, 8.1 mmol), 9-(6-bromopyridin-2-yl)-9H-carbazole (2.6 g, 8.1mmol), Pd₂(dba)₃ (0.15 g, 0.16 mmol), SPhos (0.13 g, 0.33 mmol) andK₃PO₄ (5.2 g, 24.4 mmol) in toluene (100 ml) and water (25 ml) wasrefluxed at 110° C. under nitrogen overnight. After cooling to roomtemperature, it was diluted with water. The solid was collected byfiltration and washed with large amount of water and ethanol, dissolvedin boiling toluene (500 ml) and filtered through a short plug of silicagel. Upon evaporation off the solvent, the crude product was trituratedwith boiling ethyl acetate and cooled to room temperature to yieldCompound 53 (3.5 g, 79%) as a white solid.

Device Examples

All devices were fabricated by high vacuum (˜10⁻⁷ Torr) thermalevaporation. The anode electrode was 120 nm of indium tin oxide (ITO).The cathode consisted of 1 nm of LiF followed by 100 nm of Aluminum. Alldevices were encapsulated with a glass lid sealed with an epoxy resin ina nitrogen glove box 1 ppm of H₂O and O₂) immediately after fabrication,and a moisture getter was incorporated inside the package.

All device examples had organic stacks consisting of, sequentially, fromthe ITO surface, 10 nm thick of Compound A as the hole injection layer(HIL), 30 nm of 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (α-NPD),as the hole transporting layer (HTL), and 300 Å of inventive hosts orcomparative hosts doped with 10 wt % of Compound A as the emissive layer(EML). On the top of the EML, 5 nm of Compound BL was deposited as ahole blocking (BL) and then followed by 45 nm oftris(8-hydroxyquinolinato)aluminum (Alq₃) as the ETL. The comparativeExamples were fabricated similarly to Device Example 1, except thatCompounds B, C, D and CBP were used as the emitter in the EML,respectively.

The device structures of the device example and comparative examples areshown in Table 2. The device results and data are summarized in Table 3and Table 4 from those devices. As used herein, NPD, Alq, Compound A,Compound B, Compound C, Compound D, Compound BL and Compound CBP havethe following structures:

TABLE 2 Device structures of inventive compounds and comparativecompounds Example HIL HTL EML (300 Å, doping %) BL ETL Example 1Compound A NPD 300Å Compound Compound A Compound Alq 450Å 100Å  1 10% BL50Å Example 2 Compound A NPD 300Å Compound Compound A Compound Alq 450Å100Å  2 10% BL 50Å Example 3 Compound A NPD 300Å Compound Compound ACompound Alq 450Å 100Å  5 10% BL 50Å Example 4 Compound A NPD 300ÅCompound Compound A Compound Alq 450Å 100Å 53 10% BL 50Å ComparativeCompound A NPD 300Å Compound Compound A Compound Alq 450Å Example 1 100ÅB 10% BL 50Å Comparative Compound A NPD 300Å Compound Compound ACompound Alq 450Å Example 2 100Å C 10% BL 50Å Comparative Compound A NPD300Å Compound Compound A Compound Alq 450Å Example 3 100Å D 10% BL 50ÅComparative Compound A NPD 300Å CBP Compound A Compound Alq 450Å Example4 100Å 10% BL 50Å

TABLE 3 VTE device results Relative Rel- λ_(max) Relative RelativeInitial ative x y (nm) Voltage EQE Luminance LT80 Example 1 0.357 0.606528 1.09 0.90 1.02 3.41 Example 2 0.358 0.607 528 0.93 0.94 1.11 3.13Example 3 0.361 0.604 528 1.07 0.90 1.05 3.61 Comparative 0.347 0.612526 0.95 1.06 1.06 * Example 1 Comparative 0.353 0.609 528 0.95 0.971.19 1.78 Example 2 Comparative 0.354 0.609 526 1.00 1.00 1.00 1.00Example 4 *Device did not survive annealing at 100° C. due to low Tg ofthe host. Annealing device at 100° C. for two hours before life test isour standard procedure to before obtaining device lifetime. Therefore nolifetime data was measured with device B.

TABLE 4 VTE device results Relative Rel- λ_(max) Relative RelativeInitial ative x y (nm) Voltage EQE Luminance LT80 Example 4 0.361 0.604532 0.95 1.26 1.11 1.50 Comparative 0.352 0.605 528 1.00 1.00 1.00 1.00Example 3

Table 3 and 4 summarize the performance of the devices. The drivingvoltage and external quantum efficiency (EQE) were measured at 1000nits, while the lifetime (LT_(80%)) was defined as the time required forthe device to decay to 80% of its initial luminance under a constantcurrent density of 40 mA/cm². All devices have essentially same emissioncolor, which is from the emission of Compound A. Devices with inventivecompounds as host show much improved performance compared to thecomparative examples. Inventive compounds have at least two aryl ringsbetween the triphenylene and carbazole group with a phenylene groupdirectly connected to triphenylene. This feature extended the devicelifetime unexpectedly, Comparative compounds shown above do not havethis feature. For example, Compound B has a triphenylene group connectedto a meta terphenyl. Compound C has only one phenylene group between thetriphenylene group and carbazole group. Compound D has a pyridine groupdirectly connected to triphenylene. CBP has no triphenylene group. It iscan be clearly seen from the tables, Device examples 1, 2, 3, and 4 usedCompound 1, 2, 5, and 53 as host. It shows the device lifetime(LT_(80%)) is significantly improved when they are compared with thecomparative examples while keeping the similar performance with otherparameters, such as voltage and EQE. For example, the device lifetime ofcompound 1 is more than 3.4 times better than CBP. These results havedemonstrated the unexpected advantages of using the current inventedcompounds in OLED device. The results from table 4 show the benefit ofhaving a phenylene group directly connected to triphenylene compared toa pyridine group in Compound D. Not only is the device lifetime ofdevice example 450% better than the comparative example, but also theEQE is 26% better.

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore include variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. It is understood that various theories as to whythe invention works are not intended to be limiting.

What is claimed is:
 1. A compound having a structure selected from thegroup consisting of formula II, III, IV, and V:

wherein R¹, R², R³, R⁴, R⁵, and R⁶ each represent mono, di, tri, tetrasubstitutions, or no substitution; R⁹ represents mono, di, trisubstitutions, or no substitution; R¹, R², R³, R⁴, R⁵, R⁶, and R⁹ areeach independently selected from the group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof; A¹, A², A³, A⁴, and A⁵ are each C; n is an integer from 1 to20; and wherein, if the compound has a structure of formula (II) orformula (IV): (a) n is an integer from 2 to 20, or (b) at least one ofR₁-R₆, and R₉ is not hydrogen, or (c) both (a) and (b) are true.
 2. Thecompound of claim 1, wherein the compound has a structure of formula IV:


3. The compound of claim 1, wherein the compound has a formula VI:

wherein R⁷ and R⁸ are each independently selected from the groupconsisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof.
 4. The compound of claim1, wherein R¹, R², R³, R⁴, R⁵, R⁶ and R⁹ are each independently selectedfrom the group consisting of hydrogen, deuterium, silyl, aryl, andheteroaryl.
 5. The compound of claim 1, wherein n is an integer from 1to
 5. 6. The compound of claim 1, wherein n is an integer from 1 to 3;and R¹, R², R³, R⁴, R⁵, R⁶ and R⁹ are each independently selected fromthe group consisting of hydrogen and phenyl.
 7. The compound of claim 6,wherein n is 1; and R¹, R², R³, R⁴, R⁵, R⁶ and R⁹ are hydrogen.
 8. Thecompound of claim 1, wherein n is
 2. 9. A first device comprising anorganic light-emitting device, further comprising: an anode; a cathode;and an organic layer, disposed between the anode and the cathode,comprising a compound having a structure selected from the groupconsisting of formula II, III, IV, and V:

wherein R¹, R², R³, R⁴, R⁵, and R⁶ each represent mono, di, tri, tetrasubstitutions, or no substitution; R⁹ represents mono, di, trisubstitutions, or no substitution; R¹, R², R³, R⁴, R⁵, R⁶, and R⁹ areeach independently selected from the group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof; A¹, A², A³, A⁴, and A⁵ are each C; n is an integer from 1 to20; and wherein, if the compound has a structure of formula (II) orformula (IV): (a) n is an integer from 2 to 20, or (b) at least one ofR₁-R₆, and R₉ is not hydrogen, or (c) both (a) and (b) are true.
 10. Thefirst device of claim 9, wherein R¹, R², R³, R⁴, R⁵, R⁶ and R⁹ are eachindependently selected from the group consisting of hydrogen, deuterium,silyl, aryl, and heteroaryl.
 11. The first device of claim 9, whereinthe organic layer is an emissive layer and the compound of the formula Iis a host.
 12. The first device of claim 11, wherein the organic layerfurther comprises an emissive dopant.
 13. The first device of claim 12,wherein the emissive dopant is a transition metal complex having atleast one ligand selected from the group consisting of:

wherein R_(a), R_(b), and R_(c) may represent mono, di, tri or tetrasubstitutions; R_(a), R_(b), and R_(c) are independently selected fromthe group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof; and two adjacentsubstituents of R_(a), R_(b), and R_(c) are optionally joined to form afused ring.
 14. The first device of claim 9, wherein the organic layeris a blocking layer and the compound having the formula I is a blockingmaterial in the organic layer.
 15. The first device of claim 9, whereinthe organic layer is an electron transporting and the compound havingformula I is an electron transporting material in the organic layer. 16.The first device of claim 9, wherein the first device is a consumerproduct.
 17. The first device of claim 9, wherein the first device is anorganic light-emitting device.
 18. The first device of claim 9, whereinthe first device comprises a lighting panel.
 19. A compositioncomprising a compound of claim
 1. 20. The first device of claim 9,wherein the compound of the formula I is selected from the groupconsisting of:


21. The compound of claim 1, wherein the compound is selected from agroup consisting of: